Recent Studies on Occurrence, Biosynthesis, Synthesis and Application of 2-Deoxy-Sugars: A Review

Abstract

Deoxy sugars, which have been found ubiquitously in plants, fungi, and bacteria, are an important class of carbohydrates. The widespread occurrence of deoxy sugars in different organisms suggests diverse biological functions. Numerous reports have shown that they indeed exhibit various vital and potent biological activities. In deoxy sugars, one or more hydroxyl groups of the pyranose or furanose ring are substituted by hydrogen. A well-known example is 2-deoxyribose (2-deoxy-β-D-erythro-pentofuranose), which is a component of deoxyribonucleotides, the repeating units of deoxyribonucleic acids (DNA). On the other hand, 2-Deoxy sugars are present in numerous biologically active natural products such as compactin, olivimycin, mithramycin, daunomycin, calicheamicin, etc. Deoxy sugars may be synthesized by reductive methods, using as starting materials epoxides, thio sugars, glycals, halogenated glycals, carboxylate esters, sulfonates, or even by direct reduction of hydroxyl groups. The lack of substituents at the C2 position, which serve as directing groups, renders the synthesis of 2-deoxy sugar challenging, as it often results in the nonselective formation of anomeric mixtures. Also, sugars lacking the C2 oxygenation are less stable towards the acid-catalysed hydrolysis compared to their 2-hydoxylated analogues. Therefore, this review paper presents some topics about the occurrence, biosynthesis, preparation, and applications of 2-deoxy sugars.